Rust: What is the difference between sync::RwLock and tokio::sync::RwLock?

sync::RwLock — blocking. tokio::sync::RwLock — async.

sync::RwLock:

• Blocking.
• Blocks thread.
• For sync code.

tokio::sync::RwLock:

• Async.
• Non-blocking.
• For async code.

1// Blocking
2use std::sync::RwLock;
3let lock = RwLock::new(5);
4let r = lock.read().unwrap();
5
6// Async
7use tokio::sync::RwLock;
8let lock = RwLock::new(5);
9let r = lock.read().await;

Key: std for blocking, tokio for async.